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    Subject[PATCH 5.10 162/530] spi: stm32: drop devres version of spi_register_master
    Date
    From: Antonio Borneo <antonio.borneo@foss.st.com>

    [ Upstream commit 8d559a64f00b59af9cc02b803ff52f6e6880a651 ]

    A call to spi_unregister_master() triggers calling remove()
    for all the spi devices binded to the spi master.

    Some spi device driver requires to "talk" with the spi device
    during the remove(), e.g.:
    - a LCD panel like drivers/gpu/drm/panel/panel-lg-lg4573.c
    will turn off the backlighting sending a command over spi.
    This implies that the spi master must be fully functional when
    spi_unregister_master() is called, either if it is called
    explicitly in the master's remove() code or implicitly by the
    devres framework.

    Devres calls devres_release_all() to release all the resources
    "after" the remove() of the spi master driver (check code of
    __device_release_driver() in drivers/base/dd.c).
    If the spi master driver has an empty remove() then there would
    be no issue; the devres_release_all() will release everything
    in reverse order w.r.t. probe().
    But if code in spi master driver remove() disables the spi or
    makes it not functional (like in this spi-stm32), then devres
    cannot be used safely for unregistering the spi master and the
    binded spi devices.

    Replace devm_spi_register_master() with spi_register_master()
    and add spi_unregister_master() as first action in remove().

    Fixes: dcbe0d84dfa5 ("spi: add driver for STM32 SPI controller")

    Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
    Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
    Link: https://lore.kernel.org/r/1615545286-5395-1-git-send-email-alain.volmat@foss.st.com
    Signed-off-by: Mark Brown <broonie@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/spi/spi-stm32.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
    index 53c4311cc6ab..8d8a32d46f2d 100644
    --- a/drivers/spi/spi-stm32.c
    +++ b/drivers/spi/spi-stm32.c
    @@ -1950,7 +1950,7 @@ static int stm32_spi_probe(struct platform_device *pdev)
    pm_runtime_set_active(&pdev->dev);
    pm_runtime_enable(&pdev->dev);

    - ret = devm_spi_register_master(&pdev->dev, master);
    + ret = spi_register_master(master);
    if (ret) {
    dev_err(&pdev->dev, "spi master registration failed: %d\n",
    ret);
    @@ -1987,6 +1987,7 @@ static int stm32_spi_remove(struct platform_device *pdev)
    struct spi_master *master = platform_get_drvdata(pdev);
    struct stm32_spi *spi = spi_master_get_devdata(master);

    + spi_unregister_master(master);
    spi->cfg->disable(spi);

    if (master->dma_tx)
    --
    2.30.2


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